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cesariojpn

Question about reference marks

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There are several marks along a highway that has "easy" road access, and looking at one, I noticed something.

 

http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=TU3090

http://www.geocaching.com/mark/details.aspx?PID=TU3090

 

Now originally, I reported that the route to the marker was being paved and access was closed. Now I find out it's open back again and upon re-review of the info, RM1 is in the middle of a "graveyard" on the site. My question is, how far are RM's spaced out? Is it "uniform" or does it vary from site to site? (For example PID ABXXXX has RM's spaced 35 feet apart, while ABYYYY has RM's spaced 45 feet apart) Also, for Waymarking & Geocaching recording, if I can't find RM1, do I list the PID as a partial recovery/poor recovery (I found all but one of the listed RM's), or so long as the main BM is intact, just forget about it?

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My question is, how far are RM's spaced out? Is it "uniform" or does it vary from site to site? (For example PID ABXXXX has RM's spaced 35 feet apart, while ABYYYY has RM's spaced 45 feet apart) Also, for Waymarking & Geocaching recording, if I can't find RM1, do I list the PID as a partial recovery/poor recovery (I found all but one of the listed RM's), or so long as the main BM is intact, just forget about it?

 

I am not sure of USGS reference marks. USC&GS (NGS) reference marks are "usually" within 30 meters of the station, as noted by George in his excellent pinned triangulation station tutorial at the beginning of the benchmark forums here. Here is a link and excerpt from it:

 

http://forums.Groundspeak.com/GC/index.php?showtopic=185361

 

REFERENCE MARKS - Reference Marks (RM) were set to assist in locating the Triangulation Station and also to help determine if the Triangulation Station was undisturbed in its original position. The measured directions and distances to them could also be used to reset a station mark if required. Reference Marks were factory stamped with “REFERENCE MARK” and with an arrow used to point in the direction to the Triangulation station. The original surveyor stamped the RM with the name of the Triangulation Station plus the number of the RM, just prior to setting. For example, the first RM for station JONES would be stamped “JONES NO. 1 1936”. The surveyor measured the direction and distance from the triangulation station to the Reference Mark (RM) and recorded the information as part of the station’s description. Later, if a surveyor attempting to find a Triangulation Station stumbled upon a RM first, the arrow and the published distance and direction between the RM and station would be valuable aids in the station recovery. To check the position of the Triangulation Station, the new surveyor could measure the angles and distances to the Reference Marks and compare them to the original values. USC&GS specified a Reference Mark as early as 1913. By the 1920’s, two Reference Marks per Triangulation Station were specified. Reference Marks were usually set within 30 meters (one tape length) of the station. Reference marks were numbered clockwise from north and set about 90 degrees apart. If a RM was destroyed, a new Reference Mark would be set using the next consecutive number. The disks would be set in a concrete monument buried in the ground, or set in a drill-hole in a large structure or bedrock. This type of disk was used from about 1913 to about 1970. Although the distance and direction provided enough information to compute the positions of the RMs, it was not standard procedure to compute them. After about 1970, National Geodetic Survey REFERENCE MARK disks were used.

 

Now we have found reference marks a good distance from the station. which is really not the norm. We found reference mark 2 for the station Sicard over 900 feet away. I'm not sure if this was going to be an azimuth mark originally, then turned into a reference mark.

 

http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=CQ2664

 

I personally note in the station recovery, if the reference and azimuth marks were found and their status..........and also post a separate recovery report on the reference/azimuth mark if it has it's own bluebooked datasheet.

 

http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=CP1404

 

http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=CP2965

 

P.S. Triangulation stations (and their supporting marks) are my favorite kind to look for.

Edited by LSUFan

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cesariojpn

 

On the off chance that a professional would like to use the azimuth for a total station back-sight I will include the found azimuth HH2 Lat/Long in my NGS Recovery notes. And also try to note the GPSr bearing and actual distance between it and the Triangulation Station.

 

RM's do not always follow the clockwise from true north numbering convention and the bearings are susceptible to being transposed, so the reciprocals should be checked.

 

kayakbird

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I don't recall ever seeing RMs more than 30 m/100 ft from a triangulation station, whether USGS or USCGS/NGS. Azimuth marks vary a lot more, maybe from less than 1/4 mile to a couple miles.

 

Note on the data sheet the distance and approximate bearing of the RMs is given in what is sometimes referred to as the "box score". Thus RM1 is 12.403 meters (40.69 ft) from this tri station at azimuth 042 deg 30 minutes. That's degrees to the right from geodetic north (not magnetic, so correct your compass), making this one almost northeast.

TU3090|---------------------------------------------------------------------|
TU3090| PID    Reference Object                     Distance      Geod. Az  |
TU3090|                                                           dddmmss.s |
TU3090| CN5466 KILEA RM 1                           12.403 METERS 04230     |
TU3090| TU3130 MOLOKINI LIGHTHOUSE 1950            APPROX.24.3 KM 1485849.9 |
TU3090| CN5467 KILEA RM 2                           11.896 METERS 16949     |
TU3090|---------------------------------------------------------------------|

Some older data sheets may have azimuths given in the text description. In those cases, be on the lookout for the use of an older convention of giving azimuth from south instead of from north.

 

It is good practice to note the RMs and AZ mark if found and their condition in your report, but the overall found/NF selection is made solely on the disk for which the data sheet is titled, and the RMs absence or condition do not affect that selection.

 

Note also, that GOOD/POOR/DESTROYED applies not to the appearance of the disk, but rather to how well it marks the position in space that was measured. A solidly set disk that someone hammered on but still has its punch mark for position can be GOOD with a note as to the vandalism. A pristine disk in a leaning concrete post is POOR at best.

Edited by Bill93

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We have found several, here is one.

 

HALF GQ0276 - Note: We found half of HALF - the remains of HALF and Ref. mark 1.

 

NGS DATA SHEET - So you can go to see the box score.

 

HALF RM 1 34.519 METERS

HALF RM 2 42.849 METERS

That was just a quick search of all of our finds. If you want another, you might talk us into searching further.

 

Shirley~

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I agree that RMs are usually withing a tape's length of the station, but I have at least one notable exception, NINE in Lancaster County, PA has a reference mark that is 100 meters from the station!

JV4771|---------------------------------------------------------------------|
JV4771| PID    Reference Object                     Distance      Geod. Az  |
JV4771|                                                           dddmmss.s |
JV4771|        NINE RM 1                           156.530 METERS 01940     |
JV4771|        NINE AZ MK                                         0895057.4 |
JV4771|        NINE AZ MK 2                                       0963448.2 |
JV4771| JU3837 WASHINGTON NY AWY BCN 64            APPROX.39.6 KM 1395435.9 |
JV4771|        NINE RM 2                            63.030 METERS 16131     |
JV4771|        NINE RM 3                            11.070 METERS 18021     |
JV4771|        NINE RM 4                           100.000 METERS 33427     |
JV4771|---------------------------------------------------------------------|

 

Since this is the only surviving RM it has made finding the station nearly impossible. The tiniest error when sighting from the RM to the station, or vice versa, leads to a large distance error, plus the lack of ability to swing the tape (I only own a 50 meter tape, and to make things worse the RM is across a ROAD!) means even the distance isn't accurate. The station is also 14 inches underground. So far 4 visits have turned up nothing. Well, not nothing--I found destroyed RM 3, underground without it's concrete base and gave it to the farmer. It had been folded in half, most likely by a plow. Even more fun, it is in a large garden, so while they don't mind me digging in it, on one of my visits they had JUST spread manure on the garden. Yep, I still went after the station, and dug a 10' x 4' x 14" hole.

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Speaking of Reference Marks, this one has me confuzzled.

KV4728

HARBOR LINE 1913 RM 26

 

Harbor Line 1913 is listed as destroyed (I think). But, a station with 26 RMs??? Most of which have never been found again. The one I went searching for seemed to have been deliberately removed.

Almost as strange as the series along the Hackensack Rver, by boat, set in clay tile pipes. Think only one of them was ever found again.

 

But what is "Harbor Line"?

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Speaking of Reference Marks, this one has me confuzzled.

KV4728

HARBOR LINE 1913 RM 26

 

Harbor Line 1913 is listed as destroyed (I think). But, a station with 26 RMs??? Most of which have never been found again. The one I went searching for seemed to have been deliberately removed.

Almost as strange as the series along the Hackensack Rver, by boat, set in clay tile pipes. Think only one of them was ever found again.

 

But what is "Harbor Line"?

 

Harry, I don't believe these are Reference Marks for a triangulation station (or in the sense we are used to)

 

Using DSWorld, I was able to get the marks that have that name and they appear to surround Newark Bay. I think these were placed to help in building Port Newark itself. Wikipedia states that the construction of Port Newark was begun in 1910 and accelerated in WW1...which would coincide with the 1913 date.

 

http://en.wikipedia.org/wiki/Newark_Bay

 

An online real estate dictionary defines Harbor Line:

 

An arbitrary line set by authorities on navigable rivers, beyond which wharves and other structures may not be built. Also designated as line of navigation.

 

Here is a pic I made from Google earth with the Harbor Line 1913 RM's plotted...so you can see they go around the perimeter of Newark Bay.

 

5298e146-a6dc-426d-821b-29a747c58ac9.jpg?rnd=0.4793469

 

You got you a good question here. Maybe the wiser ones than I can answer it correctly. I'm just guessing.

Edited by LSUFan

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# 4 was GeoLogged in 2009 and 2010 - no photos. Some great too far away targets here! MEL

 

HARBOR LINE 1913 RM 4

 

Shall we say that those finds do not sound credible, since that's the middle of a parking lot? But we shall have to give it a hunt sometime. Though I would love to know what they did find...

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